A137288 Numbers k such that 2*prime(k)-1 is prime.

1, 2, 4, 8, 11, 12, 22, 25, 34, 37, 46, 47, 50, 58, 63, 67, 68, 73, 75, 85, 95, 101, 106, 110, 111, 114, 121, 125, 129, 141, 145, 151, 159, 163, 168, 169, 180, 193, 203, 207, 211, 222, 226, 232, 242, 254, 258, 260, 274, 285

Offset: 1

Author

Ctibor O. Zizka, Apr 05 2008

Keywords

• easy
• nonn

Examples

			k=11: 2*prime(11) - 1 = 2*31 - 1 = 61 is prime, so k=11 belongs to the sequence.
		

Links

• Carl R. White, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000040, A005382 (corresponding primes).

Programs

Mathematica

Select[Range[285],PrimeQ[2Prime[#]-1]&] (* James C. McMahon, May 22 2025 *)

Extensions

More terms from Paolo P. Lava, Apr 15 2008